Prep for 6.1 release

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3489 42af7a65-404d-4744-a932-0658087f49c3

ReleaseNotes

@@ -1777,3 +1777,50 @@ important bugfixes.  These include:
 
 Please see the ChangeLog for details.
 
+nuttx-6.1
+^^^^^^^^^
+
+The 68th release of NuttX, Version 6.1, was made on April 10, 2011 and is
+available for download from the SourceForge website.  The 6.0 release
+introduced a detach-able application environment to build applications
+outside of the NuttX source tree.  The primary purpose of this release
+is to correct numerous build problems introduced by that architectural
+change:
+
+    * In many newer environments, NuttX produced strange Makefile errors
+      but built correctly in older environments.  A fix provided by
+      Rafael Norinha was incorporated and is reported to fix those build
+      problems.
+    * The apps/ directory build system would not handle Windows-native
+      toolchains due to obscure path formatting issues.
+    * And other problems as detailed in the change log.
+
+Many additional changes were made in the 6.1 release for another major
+architectural change:  NuttX will now build as a seperately linked micro-
+kernel.  In this build option the RTOS builds as a kernel, applications
+build separtate and interface with kernel via system calls.  Applications
+run in user mode and kernel logic users in kernel-mode.  This provides a
+secure environment for NuttX.  This feature is fully coded in NuttX-6.1,
+but has not been tested due to higher priority tasks that have arisen.
+
+Related to this change, support for the Cortex-M3 memory protection unit (MPU) has
+been integrated with the NuttX kernel build to provide an even higher level
+of security.
+
+NOTE: This kernel build is an option; the default build configuration is
+still the standard, flat, unsecured RTOS as in previous releases.
+
+Additional new features in this release:
+
+    * Support for LPC17xx GPIO interrupts (with much support from Decio Renno).
+    * Basic timer support for STM32 (Contributed by Uros Platise)
+    * A binfs file system.  This is a tiny psuedo file system that lets
+      named appliations to be viewed and accessed in NSH under the /bin
+      directory.
+    * An I2C-based driver for the LIS331DL MEMS motion sensor (Contributed
+      by Uros Platise).
+    * A board configuration for the Embedded Artists LPCXpresso LPC1768 board.
+    * The user_initialize() interface has been removed.
+
+And several bugfix associated with SD drivers, openddir(), signed 8-bit types
+(int8_t), and USB serial device.  See the ChangeLog for details.